Field of the Present Disclosure
The aspects of the disclosed embodiments are directed to the field of cabinet x-ray imaging of excised human tissue, and more specifically, to a system and method for obtaining and processing cabinet x-ray image data for tomosynthesis reconstruction allowing for a three-dimensional image of the specimen with the capability of attaining images of the specimen with geometric magnification and the purpose of such devices, as described in U.S. Pat. No. 9,138,193 Lowe, et. al., entitled “Specimen Radiography with Tomosynthesis in a Cabinet,” the disclosure of which is hereby incorporated by reference in its entirely in the present application.
Description of the Related Art
Imaging of a patient's tissue has become a common screening tool and/or diagnostic aid in modern medicine. Breast cancer remains an important threat to women's health and is the most common cancer among women today. One strategy for dealing with breast cancer is early detection of the cancer so that it may be treated prior to the cancer metastasizing throughout the body. This causes an increase in the number of surgical procedures performed involving excision of cancerous tissue or calcifications, such as ductal carcinoma in situ (DCIS).
The excision of Ductal carcinoma in situ (DCIS) is a challenging task. In order to assure that the complete DCIS lump including a cancer-free margin has been excised, the following steps may be undertaken. A pre-operational planning based on mammograms is performed carefully in order to assess the size and the location of the lump. The location of the lump is marked utilizing guide wires/markers. During the lumpectomy, the excised tissue is examined using x-ray imaging in order to assess whether its margin is cancer-free. If it is found that the excised specimen has an insufficient margin of cancer-free tissue, the surgeon removes more tissue.
Currently, x-ray images obtained are only available in two-dimensional mode and as such orthogonal views of the sample must be obtained by physically rotating the specimen to verify the margins. The breast surgeon relies on the radiogram to verify removal of the complete lump. If necessary, the breast surgeon may have to identify additional breast tissue that must be excised to ensure a clear margin. This can be an error prone and time consuming task that is performed under significant time pressure whilst the anesthetized patient is still lying on the operating table.
In typical x-ray imaging, a patient's breast sample is immobilized and contained in a specimen container. The sample is placed between an x-ray source and a digital imaging device (detector) to create a two-dimensional radiographic image of the sample. To ensure that margins are attained, at least 2 orthogonal images must be taken of the sample (90 degrees apart). The problem that arises with the above scenario is that the tissue, being somewhat fluid, may displace when it is imaged in either position, which may cause a false measurement to the breast surgeon. It would be advantageous to be able to image the sample from a greater number of different positions of the source and receptor relative to the sample while maintaining the sample stationary or in a fixed position.
Digital tomosynthesis combines digital image capture and processing with simple tube/detector motion as used in conventional radiographic tomography. Although there are some similarities to CT, it is a separate technique. In CT, the source/detector makes a complete 360-degree rotation about the subject obtaining a complete set of data from which images may be reconstructed. In digital tomosynthesis, a small change of flux created by only a small rotation angle with a small number of exposures are used. This set of data can be digitally processed to yield images similar to conventional tomography with a limited depth of field. However, because the image processing is digital, a series of slices at different depths and with different thicknesses can be reconstructed from the same acquisition, saving time.
Image data taken at the different imaging positions can be processed to generate tomosynthetic images of selected slices of the sample. The images can be of thin slices, essentially planar sections through the specimen, as in CT slices. Alternatively they can be varying thickness.
The isocenter of the image acquisition geometry is located below the sample, on the surface of the detector. The phase shifts created as a result of this arrangement are compensated for, while processing the resultant dataset. The tomosynthetic images are then generated from the generated data set.
There may be cases where magnification of the specimen should be obtained to provide a better image or visualization of the anomalies present. Digital magnification can distort and/or pixelate an image at an “x” magnification whereas a geometric magnification would provide a magnification of an “x” power without any distortion of the sample.
It is believed that no cabinet specimen tomosynthesis systems utilizing geometric magnification are commercially available currently for clinical use in specimen imaging, and that improvements in x-ray imaging and tomosynthesis are a desired goal. Accordingly, it is believed that there is a need for improved and practical tomosynthesis of breast specimens with the capability of geometric magnification
It would be advantageous to have a cabinet x-ray system for specimen imaging that could create, via digital tomosynthesis, a three-dimensional image for the breast surgeon to ensure that a proper margin around the diseased tissue has been excised in an expedient manner.
To address this, in one aspect of the present disclosure include a sample tray holding the specimen may be elevated in the sample chamber above the detector to allow for a geometric magnification of the specimen imaged and to create images which would compensate and/or delete digital distortion.